Related background prior art (incorporated herein by reference) includes the following patents as well as the prior art cited in each:
U.S. Pat. No. 4,703,027 issued Oct. 27, 1987 to Texaco Inc as assignee of Edward T. Marquis et al.
U.S. Pat. No. 4,891,437 issued Jan. 2, 1990 to Texaco Inc as assignee of Edward T. Marquis et al.